The present invention relates to a method and apparatus for conducting a non-destructive test on a container. More specifically, the invention provides for examining he internal components of a sealed container to determine if a component that has been previously secured in-place on a mounting structure within the sealed container has broken loose from its mounting structure.
Undersea fiber optic communication systems carry ever-increasing amounts of information. These systems are installed in-place under the oceans of the world and carry a large majority of the information that is transmitted between the world's continents. These fiber optic transmission systems remain in-place on the bottom of the ocean under thousands of fathoms, and even miles, of water for years at a time. Due to the difficulties encountered when having to repair, replace, or generally service these systems, it is desirable that these systems be highly reliable.
Long distance undersea fiber optic transmission systems include fiber optic repeaters at regular intervals that regenerate the optical signals that are received at the repeaters so that the transmitted signal does not become so attenuated during its transmission that it cannot be interpreted at the receiving station. Because these repeaters are installed under the sea and rest on the sea bottom, these repeaters must be hermetically sealed and must be formed of a rugged structure to prevent the sensitive optical components that are installed within the repeater from the environmental and other forces that may be applied to the repeater. Typically, the repeater is formed as a cylindrical container that is made from approximately one-inch thick beryllium copper. Once the internal optical components are installed within the cylinder, covers are welded onto its ends. Thus, once the cylinder is sealed, it is difficult to examine the internal components of the repeater.
Whereas the operation of the repeater may be verified by transmitting optical signals through the repeater and analyzing those optical signals, because the repeater is installed under the sea and is accessible only with great difficulty, it may be desirable to determine if there are any potential problems with the repeater that may not be discoverable by an operational analysis. One of these other potential problems could be a loose component within the repeater that, whereas the loose component has not yet affected the operation of the repeater, it could affect its operation at some point in the future; possibly at a time when the repeater is not easily accessible. An example could be a rivet or a screw that has become loose within the repeater. Whereas the loose rivet or screw may not affect the operation of the repeater when the operational analysis is conducted, as forces are applied to the repeater, the loose component could impact and damage optical components within the repeater. These forces may not be realized until the repeater is installed under the sea. Thus, whereas a repeater could be functioning as designed when it is operationally analyzed, the repeater could have a previously undiscoverable problem that could affect its operation in the future. Currently, it is not known how to audibly detect this type of defect. Whereas the loose component may generate a noise within the repeater as a result of impacting other components, this noise is not audible with the naked ear because of the thickness of the copper walls of the sealed repeater.
Therefore, it would be desirable to provide an apparatus and method for examining the internal components of a sealed container. This apparatus and method could be utilized to examine sealed containers before they are installed in locations where they may not be easily accessible. Similarly, the apparatus and method could be utilized to examine containers that have been previously installed in difficult to access locations and which are later accessible due to relocation of the container, etc. Thus, the apparatus and method would provide a diagnostic capability that could be utilized at any point in the life cycle of the sealed container.